Active Suppression of Major Histocompatibility Complex Class II Gene Expression during Differentiation from B Cells to Plasma Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS 1988-04, Vol.85 (7), p.2229-2233
• Main Authors: Latron, France, Jotterand-Bellomo, Martine, Maffei, Antonella, Scarpellino, Leonardo, Bernard, Michel, Strominger, Jack L., Accolla, Roberto S.
• Format: Article
• Language: English
• Subjects: ANIMAL CELLS; ANIMALS; ANTIGENS; B lymphocytes; B-Lymphocytes - cytology; BASIC BIOLOGICAL SCIENCES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BODY FLUIDS; BONE MARROW CELLS; Burkitt Lymphoma - pathology; CARBOHYDRATES; CELL DIFFERENTIATION; CELL FLOW SYSTEMS; Cell lines; CHROMOSOMES; CONNECTIVE TISSUE CELLS; DAYS LIVING RADIOISOTOPES; Gene Expression Regulation; GENE REGULATION; Genes, MHC Class II; Genetic loci; GLUCOPROTEINS; GLYCOPROTEINS; Histocompatibility Antigens Class II - biosynthesis; Histocompatibility Antigens Class II - genetics; Humans; Hybrid Cells - metabolism; Hybridity; HYBRIDIZATION; IMMUNITY; ISOTOPES; KARYOTYPE; LEUKOCYTES; LIGHT NUCLEI; LYMPHOCYTES; MAMMALS; MAN; MATERIALS; MESSENGER-RNA; MHC class II genes; MICE; NUCLEI; NUCLEIC ACIDS; ODD-ODD NUCLEI; ORGANIC COMPOUNDS; Phenotype; PHOSPHORUS 32; PHOSPHORUS ISOTOPES; PLASMA CELLS; Plasma Cells - cytology; Plasmacytoma - pathology; PRIMATES; PROTEINS; RADIOISOTOPES; RNA; RODENTS; SACCHARIDES; SOMATIC CELLS; TRANSCRIPTION; Transcription Factors - metabolism; Tumor Cells, Cultured - pathology; VERTEBRATES 550401 > Genetics-- Tracer Techniques
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.85.7.2229

Constitutive expression of major histocompatibility complex class II genes is acquired very early in B-cell ontogeny and is maintained up to the B-cell blast stage. Terminal differentiation in plasma cells is, however, accompanied by a loss of class II gene expression. In B cells this gene system is under the control of several loci encoding transacting factors with activator function, one of which, the aIr-1 gene product, operates across species barriers. In this report human class II gene expression is shown to be extinguished in somatic cell hybrids between the human class II-positive B-cell line Raji and the mouse class II-negative plasmacytoma cell line P3-U1. Since all murine chromosomes are retained in these hybrids and no preferential segregation of a specific human chromosome is observed, the results are compatible with the presence of suppressor factors of mouse origin, operating across species barriers and inhibiting class II gene expression. Suppression seems to act at the level of transcription or accumulation of class II-specific mRNA, since no human, and very few murine, class II transcripts are detectable in the hybrids.